Postop radiation deferral ‘higher-than-expected’ in paediatric medulloblastoma
medwireNews: Postoperative radiotherapy is being increasingly deferred in medulloblastoma patients aged between 3 and 8 years, report US researchers who also find that deferral is associated with worse survival.
Their analysis of data from the US National Cancer Data Base registry revealed “a higher-than-expected” rate of postoperative radiotherapy deferral among children of this age group given that deferral is “less supported” in children of 3 years and older, while being generally accepted for younger patients.
Of 816 children with medulloblastoma aged 3–8 years who underwent surgery and adjuvant chemotherapy between 2004 and 2012, 15.1% either did not receive postoperative radiotherapy or initiated it more than 90 days after surgery (deferred group). The remaining 84.9% received radiotherapy upfront, that is, within 90 days of undergoing surgery.
Multivariate analysis showed that deferral was significantly associated with age, such that older patients were less likely to defer radiotherapy, with an odds ratio (OR) of 0.57 per year and deferral rates ranging from 36.8% for 3-year old patients to 4.1% for those aged 8 years.
Year of diagnosis was the only other significant parameter (OR=1.18 per year), with deferral rates increasing between 2004 and 2012. During the study period, the deferral rate was lowest in 2005, at 8.1%, and rose to a high of 27.1% in 2012, report Benjamin Kann (Yale University School of Medicine, New Haven, Connecticut) and co-authors in JAMA Oncology.
They also evaluated survival among a subset of 474 patients who were followed up for a median of 4.8 years. Five-year overall survival (OS) was significantly poorer for the 83 patients for whom postsurgery radiotherapy was deferred compared with the 391 who received it upfront, at 63.4% versus 82.0%.
And deferral of postoperative radiotherapy versus receiving it upfront was one of the factors that significantly predicted worse OS after adjusting for confounders, at a hazard ratio (HR) of 1.95.
Writing in a related commentary, Arnold Paulino (MD Anderson Cancer Center, Houston, Texas, USA) and Jerry Jaboin (Oregon Health & Science University, Portland, USA) do not find this result surprising, but point out that the decision to defer radiotherapy was not made before treatment began, and it is possible that reasons for delaying or avoiding treatment could include factors such as postoperative complications and poor performance status.
“Hence, there are some patients in the [radiotherapy]-deferred arm who were not going to do well regardless of further treatment because of postsurgical morbidity and the general well-being of patient.”
Nonetheless, they think that at present, paediatric medulloblastoma patients aged 3–8 years should continue to receive postoperative radiotherapy and chemotherapy.
“[H]owever, future studies using molecular subgroups for determination of treatment may reveal that some of these patients may not require [radiotherapy]”, conclude Paulino and Jaboin.
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